AC/DC type microwave oven

ABSTRACT

An AC/DC microwave oven includes a selecting switch selecting AC or DC input power; a supplier supplying power using a common driving load driven by the DC power, and supplying the AC input power or DC/AC converted power selected by the selecting switch; and a microwave oscillator driven by AC power supplied by the supplier. The AC/DC type microwave oven includes a rectifier rectifying the AC input power into DC power; driving load driven by rectified DC power or DC input power; rotatable inverter including a motor driven by the DC input power, and commutator producing AC power according to the DC input power inputted to one direction which is outputting in two directions by means of input/output brushes contacted with four directions of the commutator and rotated by a motor; and microwave oscillating part driven by the AC power converted by the rotatable inverter or the AC input power.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a microwave oven, and more particularlyto an AC/DC type microwave oven, which is capable of using an AC(alternating current) power or a DC (direct current) power selectively.

2. Description of the Background Art

The microwave oven is an appliance for heating/cooking food using amicrowave. In the microwave oven, a high voltage transformer steps up acommon power source 120/230V of the AC power to a high voltage of2,000V, and a magnetron driven by the high voltage 2,000V produces amicrowave having a predetermined frequency. The microwave oscillatesmolecules of water in food, and then food is heated/cooked by thegenerated heat.

FIG. 1 is a partial cutaway perspective view of a conventional microwaveoven.

In FIG. 1, the reference numeral 1 is a cabinet, the reference numeral 2is a cooking chamber, and the reference numeral 3 is a device chamber.The reference numeral 4 is a door, the reference numeral 5 is a tray,and the reference numeral 6 is a cover. The cabinet 1 is partitionedinto left and right spaces. At one side of the cabinet I is provided thecooking chamber 2 of which front is open. At the other side of thecabinet 2 is provided the device chamber 3 in which a variety ofelectrical devices are installed.

At the upper and side of the cabinet I is provided the cover 6 thatforms the appearance of the microwave oven. The door 4 is fixed to oneside of the cabinet I which is capable of pivoting so that the front ofthe cooking chamber 2 can be opened/closed thereby. The tray 5 isinstalled at the bottom of the cooking chamber 2, and food to be cookedis loaded on the tray 5. The tray 5 is rotated by a driving motor(notshown) installed at the lower side thereof.

The reference numeral 7 designates a control panel. The referencenumeral 8 designates an air guide, and the reference numeral 9designates a cooling fan. HVT, HVC, HVD and MGT designate a high voltagetransformer, a high voltage condenser, a high voltage diode and amagnetron, respectively. They are installed in the device chamber 3, andare connected electrically with each other. The high voltage transformerHVT transforms a common alternating current AC into a high voltage, andthe high voltage is doubled by the high voltage condenser HVC and thehigh voltage diode HVD (which is 4,000V approximately). Then, thedoubled high voltage is applied to the magnetron MGT, and then a 2,450MHz (megahertz) microwave is generated by the magnetron MGT.

The control panel 7 is installed at the front side of the device chamber3, through which a user operates the microwave oven, and the operationalstate of the microwave oven is displayed.

The cooling fan 9 cools the magnetron MGT and the high voltagetransformer HVT by blowing forced air. The air guide 8 is installed nearthe magnetron MGT so that the air heated during the cooling operation ofthe magnetron MGT is guided into the cooking chamber 2.

FIG. 2 is a block diagram of AC/DC type microwave oven according to theprior art, and FIG. 3 is a schematic diagram of FIG. 2.

In FIG. 2, AC/DC type microwave oven according to the prior art includesan AC driving load 10, a DC driving load and DC/AC converting part 20,and a microwave oscillator 30.

The AC driving load 10 is driven by an AC input power. The DC drivingload and DC/AC converting part 20 include the DC driving load beingdriven by a DC input power and the DC/AC converter converting the DCinput power into an AC power. The microwave oscillator 30 is inputted bythe power out of the AC input power or the DC/AC power converted by aDC/AC converter, and generates a 2,450 MHz (megahertz) microwave.

With reference to FIG. 3, a schematic diagram of AC/DC type microwaveoven is described as follows.

In FIG. 3, the AC input power is connected to the AC driving loads 11,and is connected to a power switch SW₁ to determine the driving statusof the AC power. The AC driving loads 11 include a lamp 12 a and acooling fan motor 12 b being operated by an AC power. The DC power isconnected to the DC driving loads 21, and is connected to a power switchSW₂ to determine the driving status of the DC power, and forms adifferential DC circuit net discriminated as an AC circuit net. The DCdriving loads include a lamp 22 a and a cooling fan motor 22 b beingoperated by a DC power.

The DC input power is connected to the DC/AC converter 23. The microwaveoscillating part 30 includes a high voltage transformer HVT whichreceives both the AC power and the DC power, a high voltage condenserHVC, a high voltage diode HVD, and a magnetron MGT. The operation of themicrowave oscillator is described the same way as shown in FIG. 1.

The operation of a conventional microwave oven having theabove-described constitution is as follows. First, the user pulls thedoor 4 so that cooking chamber 2 is opened, then places a containercontaining food on the tray 5. The user closes the door 4, switches-onthe power switch SW₁ or the power switch SW₂ selectively, and thenoperates the microwave oven. The user, however, must switch on only oneof the DC power switch SW₂ or the AC power switch SW₁ according to theinput power described. For example, in case the user switches on the ACpower switch SW₁, the AC input power supplies to the driving load thatincludes the lamp 12 a and the cooling fan motor 12 b. The AC inputpower also supplies to the high voltage transformer HVT of the microwaveoscillating part 30. When the AC power supplied to the high voltagetransformer HVT is converted to a high voltage through the high voltagecondenser HVC and the high voltage diode HVD, the high voltage issupplied to the magnetron MGT. The magnetron MGT driven by the highvoltage generates a microwave. The generated microwave radiates it intothe cooking chamber 2 for the heating/cooking of food, and then radiatesit into food uniformly when the tray 5 is rotated in the cooking chamber2. In the device chamber 3, the cooling fan 9 cools the inner devices byblowing air. The tray 5 rotates the food in order to radiate themicrowave on the food uniformly. Therefore, the food in the cookingchamber 2 is heated/cooked properly according to the cooking time andcooking temperature that have been selected by the user.

In case the user switches on the DC power switch SW₂, a DC input powersupplies to the driving load that includes the lamp 22 a and the coolingfan motor 22 b, and supplies to the DC/AC converting part 23. The DC/ACconverting part 23 converts the DC input power into an AC power, andthen the converter AC power supplies to the high voltage transformer HVTof the microwave oscillating part 30. After the converted AC powersupplied to the high voltage transformer HVT is converted to a highvoltage by the high voltage condenser HVC and the high voltage diodeHVD, the high voltage is supplied to the magnetron MGT. The magnetronMGT driven by the high voltage generates a microwave. The generatedmicrowave radiates it into the cooking chamber 2 for the heating/cookingof food.

In such a conventional AC/DC type microwave oven, the microwave ovenmust be provided with the differentiated driving loads for AC and DC,respectively. As the number of parts of the microwave increases, themanufacturing cost of the microwave oven increases.

Furthermore, in case the AC power and the DC power are selected by theuser the same time mistakenly, a conventional microwave oven increasesthe possibility of faulty operations since a conventional microwave ovencannot prevent such an occurrence.

SUMMARY OF THE INVENTION

The present invention has been made to overcome the above describedproblem of the prior art, and accordingly it is the first object of thepresent invention to provide an AC/DC type microwave oven for reducingthe manufacturing cost of the microwave oven by reducing the number ofparts of the driving loads that include a lamp and a cooling fan motordriven by the AC power.

It is the second object of the present invention to provide an AC/DCtype microwave oven to prevent the faulty operations of the microwaveoven by limiting the selection of only one of the AC power and the DCpower available.

To achieve the above objectives, the present invention provides an AC/DCtype microwave oven comprising: means for selecting an AC input power ora DC input power; means for supplying power using a common driving loadbeing driven by the DC power, and supplying the AC input power or aDC/AC converted power selected by the means for selecting; and means foroscillating the microwave being driven by the AC power supplied by themeans for suppling power.

The means for selecting comprises: one more exchanging switch forsupplying a circuit net with only one of the AC input power or the DCinput power available, when the AC input power and the DC input powerform an AC circuit net and a DC circuit net, respectively, which arediscriminated from each other.

The one more exchanging switch includes: a first exchanging switch beingconnected to a common line of the AC and DC circuit nets; a secondexchanging switch being connected to the AC circuit net; and a thirdexchanging switch being connected to the DC circuit net.

The means for supplying power includes: a rectifying part for rectifyingthe AC input power into a DC power; driving load being driven by therectified DC power or the DC input power; and DC/AC converting part forconverting the DC input power into AC power.

The rectifying part includes: a low voltage transformer to step-down theAC input power; and a bridge diode for rectifying the step-down AC inputpower into DC power.

The DC/AC converting part is a rotatable inverter for producing an ACpower according as the DC power inputted in one direction is outputtedin turn in two directions. The rotatable inverter includes: a motorbeing driven by the DC input power; and a commutator for producing an ACpower according to the DC input power being inputted in one direction isoutputting in turn in two directions by means of input/output brushesbeing contacted with four directions of the commutator and being rotatedby the motor.

To achieve the above objectives, the present invention provides an AC/DCtype microwave oven including: means for rectifying the AC input powerinto a DC power; a driving load being driven by a rectified DC power orthe DC input power; a rotatable inverter including a motor being drivenby the DC input power, and a commutator for producing an AC poweraccording to the DC input power being inputted in one direction isoutputting in turn in two directions by means of input/output brushesbeing contacted with four directions of the commutator and being rotatedby the motor; and a microwave oscillating part for being driven by theAC input power or the AC power converted by the rotatable inverter.

The means for rectifying includes: a low voltage transformer tostep-down the AC input power; and a bridge diode for rectifying thestep-down AC input power into DC power.

The means for selecting includes: one more exchanging switch forsupplying a circuit net with only one of the AC input power or the DCinput power, when the AC input power and the DC input power form an ACcircuit net and a DC circuit net, respectively which are discriminatedfrom each other.

The one more exchanging switch includes: a first exchanging switch beingconnected to a common line of the AC and DC circuit nets; a secondexchanging switch being connected to the AC circuit net; and a thirdexchanging switch being connected to the DC circuit net.

Accordingly, an AC/DC type microwave oven adopts the only driving loaddriven by the DC power, reduces the number of parts of the AC drivingload that include a lamp and a cooling fan motor driven by the AC power,and reduces the manufacturing cost of the microwave oven. Besides, theAC/DC type microwave oven can prevent the faulty operation by means ofentering selectively only one of the AC power or the DC power.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object and other advantages of the present invention willbecome more apparent by describing in detail in a preferred embodimentthereof with reference to the attached drawings, in which:

FIG. 1 is a partial cutaway view of a conventional microwave oven;

FIG. 2 is a block diagram of AC/DC type microwave oven according to theprior art;

FIG. 3 is a schematic diagram of FIG. 2;

FIG. 4 is a block diagram of AC/DC type microwave oven according to thepresent invention;

FIG. 5 is a detailed block diagram of AC/DC type microwave ovenaccording to the present invention;

FIG. 6 is a schematic diagram of AC/DC type microwave oven being drivenby an AC power according to the present invention; and

FIG. 7 is a schematic diagram of AC/DC type microwave oven being drivenby a DC power according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will become more apparent by describing in detailin a preferred embodiment thereof with reference to the attacheddrawings.

FIG. 4 and FIG. 5 are a block diagram and a detailed block diagram,respectively, according to the present invention. In FIG. 4, an AC/DCtype microwave oven includes: an AC/DC selecting switch 100 forselecting an AC input power or a DC input power; an AC supplier 200 forusing a common driving load being driven by a DC power, and forsupplying the AC input power or a converted AC power selected by theAC/DC selecting switch 100; and a microwave oscillator 300 forgenerating microwave according to being driven by the AC power in the ACsupplier 200.

FIG. 5 is a detailed schematic diagram of the AC supplier 200 in FIG. 4,and the AC supplier 200 includes: AC/DC rectifier 210 for rectifying theAC input power into a DC power; DC driving loads 220 being driven by therectified DC power or the DC input power; and DC/AC converter 230 forconverting the DC input power into AC power.

In the AC/DC type microwave oven according to the present invention, theuser selects one of the AC input power or the DC input power. If theselected power is the AC input power, the AC/DC rectifier 210 rectifythe AC input power into the DC power. The rectified DC power drives theDC driving loads 220, and the AC input power is supplied to themicrowave oscillator 300. If the selected power is the DC input power,the DC input power drives the DC driving loads 220, and then the ACinput power is supplied to the microwave oscillator 300. The DC/ACconverter 230 that is a rotatable inverter converts the DC input powerinto DC power, and then supplies to the microwave oscillator 300. Thus,the DC driving load 220 that includes a lamp or a cooling fan motor isdriven only by the DC power.

FIG. 6 and FIG. 7 are schematic diagrams of the AC/DC type microwaveoven according to the present invention. FIG. 6 shows the driving statusof the AC power, and FIG. 7 shows the driving status of the DC power.

In FIGS. 6 and 7, the reference numeral 220 is a DC driving load, thereference numeral 221 is a lamp, the reference numeral 222 is a coolingfan motor. The reference numeral 210 is an AC/DC rectifier, thereference numeral 230 is a rotatable inverter, and the reference numeral300 is a microwave oscillator. SW₁₀ and SW₂₀ are power switches. SW₃₀,SW₃₁, and SW₃₂ are exchanging switches. LVT, HVT, MGT, BD, LP1, LP2 andCL designate a low voltage transformer, a high voltage transformer, amagnetron, a bridge diode, an AC circuit net, a DC circuit net, and acommon line of the AC and DC, respectively. The AC/DC rectifier 210includes the low voltage transformer LVT to step-down the AC inputpower, and the bridge diode BD for rectifying the step-down AC power bythe low voltage transformer LVT into a DC power. Also, the DC/ACconverter 230 is a rotatable inverter that outputs an AC power in turnin two directions according to the DC input power inputted in onedirection. The rotatable inverter 230 includes a motor 231 being drivenby the DC input power; and a commutator 232 for producing an AC poweraccording to the DC input power being inputted in one direction isoutputed in turn in two directions by means of input/output brushesbeing contacted with four directions of the commutator 232 and beingrotated by the motor 231.

Selecting switch 100 includes one more exchanging switch for supplying acircuit net with only one of the AC input power or the DC input powerable to be used at one time, when the AC input power and the DC inputpower form an AC circuit net LP1 and a DC circuit net LP2, respectively,which are discriminated from each other. One more exchanging switchincludes a first exchanging switch SW₃₀ being connected to a common lineCL of the AC and DC circuit nets; a second exchanging switch SW₁₀ beingconnected to the AC circuit net LP1; and a third exchanging switch SW₂₀being connected to the DC circuit net LP2.

As shown in FIGS. 6 and 7, the AC input power and the DC input powerform circuit nets of the AC and DC, respectively, which arediscriminated from each other. The circuit nets is provided the powerswitches SW₁₀, SW₂₀ for switching on/off the respective power. The AC/DCrectifier 210 being formed in the AC circuit net LP1 rectifies the ACinput power into the DC power. The AC/DC rectifier 210 includes the lowvoltage transformer LVT to step-down the AC input power into the DCpower, and the bridge diode BD for rectifying the step-down AC powerinto the DC power. The DC driving load 220 comprises the lamp L and thecooling fan motor F driven by the rectified DC power. The rotatableinverter 230 includes a motor 231 being driven by the DC input power,and the commutator 232 for producing AC power according to the DC inputpower inputted in one direction which is in turn outputted in twodirections by means of input/output brushes (not shown) being contactedwith four directions of the commutator 232 and being rotated by themotor 231. Also, the microwave oscillator 300 is driven by the AC inputpower and the DC/AC converted power. The microwave oscillator 300includes the high voltage transformer HVT, the high voltage condenserHVC, the high voltage diode HVD, and the magnetron MGT. The operation ofthe microwave oscillator 300 was described in the prior art.

Also, for inputting selectively only one power of the AC input power orthe DC input power, selecting switches 100 include the exchangingswitches SW₃₀, SW₃₁, SW₃₂. The first exchanging switch SW₃₀ is connectedto the common line of the circuit nets, the second exchanging switchSW₃₁ is connected to the AC circuit net LP1, and the third exchangingswitch SW₃₂ is connected to the DC circuit net LP2.

In the structure of the above-mentioned, the driving status of the ACpower is described as follows with reference to FIG. 6.

The user selects a power for use according to the selection of the firstexchanging switch SW₃₀. That is, in case the user wants to use the ACpower, the AC power is supplied to the microwave oven by means ofswitching the first exchanging switch SW₃₀ connected to the common lineCL into terminal a located in the AC circuit net LP1. Therefore, thesecond exchanging switch SW₃₁ in the AC circuit net LP1 is switched on,and the third exchanging switch SW₃₂ is switched off as shown in FIG. 6.It is preferable that the second and third exchanging switches SW₃₁,SW₃₂ operate exclusively when one switch is switched-on or when anotherswitch is switched-off

The user pulls the door 4 to open the cooking chamber 2, and then placesa container containing food on the tray 5. Next, the user closes thedoor 4, then switches on the power switch SW₁₀, which operates themicrowave oven. In the AC circuit net LP1 formed a closed loop, the ACinput power is supplied to the low voltage transformer LVT within theAC/DC rectifier 210, which is supplied to the high voltage transformerHVT within the microwave oscillator 300. The low voltage transformer LVTsteps down the AC input power, and the bridge diode BD rectifies thestep-down AC power into the DC power. Then, the rectified DC power issupplied to the DC driving load 220 in the DC circuit net LP2 so as todrive the lamp L and the cooling fan motor F. When the AC power beingsupplied to the high voltage transformer HVT in the microwave oscillator300 is converted into the high voltage through the high voltagecondenser HVC and the high voltage diode HVD, the converted AC power issupplied to the magnetron MGT. The magnetron MGT driven by the highvoltage generates the microwave so as to radiate into the cookingchamber 2 for heating/cooking food.

Since the DC circuit net LP2 forms an open loop, the rotatable inverter230 connected to the DC circuit net LP2 cannot operate even though theDC power switch SW₂₀ is switched on according to the selection status ofthe AC power by means of the exchanging switches SW₃₀, SW₃₁, SW₃₂.Therefore, the microwave oven has no possibility of faulty operation.

The driving status according to the DC power is described as followswith reference to FIG. 7. The user enters the DC power into microwaveoven by means of switching the first exchanging switch SW₃₀ connected tothe common line CL into terminal b located in the DC circuit net LP2.Therefore, the second exchanging switch SW₃, in the AC circuit net LP1is switched off, and the third exchanging switch SW₃₂ is switched on asshown in FIG. 7. As shown be FIG. 1, the user pulls the door 4 to openthe cooking chamber 2, and then places a container containing food onthe tray 5. The user closes the door 4, then switches on the powerswitch SW₂₀, which operates the microwave oven. In the DC circuit netLP2 is formed a closed loop, the DC input power is supplied to the DCdriving load 220 in the DC circuit net LP2 so as to drive the lamp L andthe cooling fan motor F. The DC input power is supplied to the rotatableinverter 230, and then the motor 231 driven by the DC power rotates thecommutator 232 being inputted to one direction by means of input/outputbrushes (not shown) being contacted with four directions of thecommutator 232. The DC power converts into the AC power by means of therotation of the commutator 232. The AC power being supplied to the highvoltage transformer HVT within the microwave oscillator 300 is convertedinto the high voltage through the high voltage condenser HVC and thehigh voltage diode HVD. The converted AC power is supplied to themagnetron MGT. The magnetron MGT being driven by the high voltagegenerates the microwave to radiates into the cooking chamber 2 forheating/cooking food. Since the AC circuit net LP1 forms an open loop,the rotatable inverter 230 connected to the DC circuit net LP2 cannotoperate even though the AC power switch SW₁₀ is switched on according tothe selection status of the DC power by means of the exchanging switchesSW₃₀, SW₃₁, SW₃₂. Therefore, the microwave oven has no the possibilityof faulty operation.

In the AC/DC type microwave oven according to the above-mentionedinvention, since the AC/DC type microwave oven adopts only DC drivingload being driven by the DC power, the manufacturing cost reduces due toreduced number of parts of the AC driving load. Besides, the microwaveoven is prevented from the faulty operation by means of selecting one ofthe AC power or the DC power operations.

While the present invention has been particularly shown and describedwith reference to the preferred embodiment thereof, it will beunderstood by those skilled in the art that various changes in form anddetails may be effected therein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. An AC/DC type microwave oven comprising: meansfor selecting an AC input power or a DC input power; means for supplyingpower using a common driving load being driven by a DC power, andsupplying said AC input power or a DC/AC converted power being selectedby said means for selecting; and means for oscillating microwave beingdriven by said AC power supplied by said means for supplying power. 2.The AC/DC type microwave oven as claimed in claim 1, wherein said meansfor selecting comprises one more exchanging switch for supplying eachcircuit net with only one of said AC input power or said DC input power,when said AC input power and said DC input power form an AC circuit netand a DC circuit net, respectively, which are discriminated from eachother.
 3. The AC/DC type microwave oven as claimed in claim 2, whereinsaid one more exchanging switch comprises: a first exchanging switchbeing connected to a common line of said AC and DC circuit nets; asecond exchanging switch being connected to said AC circuit net; and athird exchanging switch being connected to said DC circuit net.
 4. TheAC/DC type microwave oven as claimed in claim 1, wherein said means forsupplying power comprises: a rectifying part for rectifying said ACinput power into a DC power; a driving load for being driven by saidrectified DC power or said DC input power; and a DC/AC converting partfor converting said DC input power into an AC power.
 5. The AC/DC typemicrowave oven as claimed in claim 4, wherein said rectifying partcomprises: a low voltage transformer to step-down said AC input power;and a bridge diode for rectifying said step-down AC input power into theDC power.
 6. The AC/DC type microwave oven as claimed in claim 4,wherein said DC/AC converting part is a rotatable inverter for producingan AC power according as a DC power being inputted to one directionwhich is outputting in turn in two directions.
 7. The AC/DC typemicrowave oven as claimed in claim 6, wherein said rotatable invertercomprises: a motor being driven by said DC input power; and a commutatorfor producing AC power according as said DC input power being inputtedto one direction is outputting in turn in two directions by means ofinput/output brushes being contacted with four directions of saidcommutator and being rotated by said motor.
 8. The AC/DC type microwaveoven as claimed in claim 1, wherein said driving load is a lamp or acooling fan motor being driven by said DC power.
 9. An AC/DC typemicrowave oven comprising: means for rectifying an AC input power into aDC power; a driving load being driven by said rectified DC power or a DCinput power; a rotatable inverter including a motor being driven by saidDC input power, and a commutator for producing AC power according assaid DC input power being inputted to one direction which is outputtingin turn in two directions by means of input/output brushes beingcontacted with four directions of said commutator and being rotated bysaid motor; and a microwave oscillating part being driven by said ACpower converted by said rotatable inverter or said AC input power. 10.The AC/DC type microwave oven as claimed in claim 9, wherein said meansfor rectifying comprises: a low voltage transformer to step-down said ACinput power; and a bridge diode for rectifying said step-down AC inputpower into a DC power.
 11. The AC/DC type microwave oven as claimed inclaim 9, wherein said means for selecting comprises one more exchangingswitch for supplying each circuit net with only one of said AC inputpower or said DC input power, when said AC input power and said DC inputpower form an AC circuit net and a DC circuit net, respectively, whichare discriminated from each other.
 12. The AC/DC type microwave oven asclaimed in claim 11, wherein said one more exchanging switch comprises:a first exchanging switch being connected to a common line of said ACand DC circuit nets; a second exchanging switch being connected to saidAC circuit net; and a third exchanging switch being connected to said DCcircuit net.